OCRa A level Chemistry Module 6 Spectroscopy Notes

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Spectroscopy 6 3
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2




NMR :
used in hospitals for MRI's (Magnetic Resonance Imaging


NMR spectroscopy involves interaction of materials with low-energy
radis waves of the electromagnetic spectrum
.

All nuclei possess charge + mass

ONLY those with odd numbers are able to spin
.




TMs etramethysilane (CHs)ySi is added to provide standard
=
a

reference signal.

used as the standard :

-




-
inert
volatile
c
non-toxic
is
-




chemical shift value of 0
.


solutions containing both carbon and hydrogen atoms must be
-




deuterated to ensure it is not picked up and no signal is shown on

the NMP spectrum
.




e .

.
g Deuterated Chloroform (CDCIs) isotopologue
: of Chloroform /CH(s)
A atom is replaced by deuterium isotope (D).
commonly used solvent when running carbon-13 +
proton
NMR spectroscopy
.

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Carbon-13 NMR



Carbon-13 NMR chemicalshift indicates the number of different
carbon environments (atoms) +
type of environment.



You can't have more peaks than numbers to catons,
-



You CAN have 11 peak ) then number of safm/.
-




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Poston NMR


Proton NMR chemical shifts indicate the

chemical environments of the protons present


e ethanol peaks
-

.


g three
It It
I ↑ at 1 3 5 and 6 alppm
- .



, ,


H


-
-
-
peaks on the proton NMR

i
spectrum :




(2H) (1H) (3H)
absorption




121110987654321


chemical sit 1 flppm